a Wii HD would just be a savage market-splitting device, especially at this point. It simply doesn't click with Nintendo's strategy of making it all as easy as possible for everyone
A better scaling device might be useful, but they're not going to do for Wii what they did for DS, it just doesn't work with consoles. A proper successor makes much more sense, something that makes the big leap into PS360 territory (i still say a processor roughly equal to the Xenos in both architecture and power with 1 GB of integrated RAM), but uses this technology not to make things more complicated, but to make them easier. Wii Team Sports, something that takes the concept of Wii Sports but applies it to more processor-intensive Team sports, like Wii Sports Football (American) or Wii Sports Soccer. I do think they will stick with the Wii name. I think the Wii brand is actually stronger than the Nintendo brand in the mass market, and Nintendo would be foolish to abandon it, unless they deign to reinvent the wheel again with their next console